creatinine levels!!! up and down!!

Hi I was wondering if anyone can give me their advice on my creatinine levels.  

I have been really unwell since may now the reasons for this are being investigated (adrenal tumour and possible POTS).  Whilst in hospital I seen a glimpse of some test results, the one that caught my eye were the one that was highlighted - creatinine level 2.2 (194.480).  The level of the previous test was 1.1 and the test after was 1.3 (i think).  When I looked this up it states that this level of creatinine (if consistant) is stage 3/4 CKD.  I am confused why my levels went up this high and then lowered again.  I was drinking lots - i'm always thirsty.  

Does anybody know why this happens and should I be concerned about this?

Thanks